Regulatory elements (e.g., transcription factors, cis-acting enhancer elements, transcriptional coactivators and chromatin regulators) activate gene expression programs in cells ranging from embryonic stem cells (ESCs) to tumor cells. Regulatory elements are important for maintenance of cell identity (e.g., ESC identity) and of some disease states (e.g., cancer). The mechanisms underlying how regulatory elements contribute to maintenance of cell identity and of disease state are not entirely understood.